Neoadjuvant rectal cancer (RC) score to predict survival: Potential surrogate endpoint for early phase trials.

384 Background: Valentini, et al. (J Clin Oncol 29: 2011, 3163-72) developed nomograms for predicting overall survival (OS) based on clinical factors available after neoadjuvant therapy (tx). Pathologic T-stage (pT), N-stage (pN), and clinical T (cT) were the most important independent predictors of OS. We developed a neoadjuvant RC score (NAR score) using pN and downstaging of T (cT – pT) based on relative weights suggested by the nomograms. NSABP’s R-04 trial presents an opportunity for independent validation of the NAR score. Methods: Pts with clinical stage II/III RC undergoing preoperative RT (4,500cGy in 25 fractions over 5 wks + boost of 540-1,080cGy in 3-6 daily fractions) were randomized to one of four regimens in a 2x2 design: CVI 5-FU (225mg/m2 5 days/wk), with or without oxaliplatin (Ox) (50mg/m2 /wk x 5) or oral capecitabine (825 mg/m2 BID 5 days/wk), with or without Ox. The NAR score is computed as [5 pN – 3 (cT – pT) + 12]2/ 9.61 where: cT in {1, 2, 3, 4}, pT in {0, 1, 2, 3, 4}, and pN in {...